Fix odoc documentation warnings across day10, js_top_worker, and extensions

Escape curly braces and fix odoc reference syntax to eliminate warnings
with (warnings fatal):
- Replace {dir}, {pkg}, {hash} etc with [dir], [<pkg>], [<hash>] or
{[ code blocks ]} as appropriate
- Fix {!Stdlib.Out_channel.with_open_gen} -> [Out_channel.with_open_gen]
in sherlodoc type_polarity.mli
- Fix @scrolly.<theme> -> [@scrolly.<theme>] in scrollycode extension
- Fix JSON format in findlibish.ml doc comment

Co-Authored-By: Claude Opus 4.6 <[e-mail]>

src/scrollycode_extension.ml

···
     - dark: Cinematic terminal aesthetic (JetBrains Mono + Outfit)
     - notebook: Clean editorial aesthetic (Newsreader + DM Sans)
 
-    Authoring format uses @scrolly.<theme> custom tags with an ordered
+    Authoring format uses [@scrolly.<theme>] custom tags with an ordered
     list inside, where each list item is a tutorial step containing
     a bold title, prose paragraphs, and a code block. *)